Amidst an enchanting landscape with beautiful islands, magnificent mountain ranges, marvellous coasts and historically famed cities, Vesuvio is the focal point, lying in the center of a plain on the ENE side of the Gulf of Napoli. It is the steepness, the abrupt way it rises from its placid surroundings, that render it so impressive. It is the imagination of how that thing must have looked like when it was erupting and how it must have been to those living close to it that give it such a feel of power.
Vesuvio in eruption, March 1944, seen from Napoli. Taken during the culminating explosive stage of the most recent eruption to date when thousands of residents had to be moved away temporarily. Allied troops had to cope with tephra fallout severely hampering use of aircraft during this decisive stage of WW-II in Italy. This rare color photo was taken from the Time Life book "Volcano".
View from the northern crest of Monte Somma (the rim of Vesuvio's caldera) down into the Valle dell'Inferno and the lower N flank of the active cone of Vesuvio. >50 years after the latest eruption have allowed intense re-vegetation of the area affected by numerous eruptions in the past 400 years. The lava flow of the 1944 eruption, however, is still free of significant vegetation, being visible in the lower part of the photo mosaic taken on 12 September 1989.
The last eruption thus far was in 1944. Since then, the population in the immediate surroundings has had a manyfold increase. Take the bus up to the "quota mille" (the terminus at 1000 m elevation on the historically active cone) from Ercolano or Toore del Greco, and for the first 25 minutes, you don't get out of the sea of houses. Upwards, the homes get more and more luxurious, accompanied by tens and more tens of hotels and pensioni. After being stricken by the massive way the volcano dominates that area, the second surprise is how green it is. Reforestation has been carried out vigorously in the 50+ years since the most recent eruption. Even the lava flow of 1944 on the caldera floor of Atrio del Cavallo, still barren in most places and still a distinct reminder of the volcano's potential, carries small trees that have appeared only during the past few years.
Vesuvio in eruption, August 1779. This eruption was a typical subcycle-closing event, characterized by the ejection of spectacular lava fountains rising several km above the summit, and devastating tephra falls in the northeast sector of the volcano. Image was taken from Alfano and Friedlaender 1928 (see references; bottom of this page).
Eruptive activity of Vesuvio obviously occurs in cycles that last several centuries and alternate with repose periods lasting several centuries as well. Each of these repose periods ends with a major (Plinian) eruption, thus initiating an active cycle. Within this active cycle, smaller subcycles acn be observed, starting with minor intracrateral (effusive and Strombolian) activity with some fluctuations until a strong eruption produces tall eruption columns, more voluminous, rapidly moving lava flows, and heavy tephra falls. This culminating, subcycle-ending eruption is followed by a brief (max. 7 years during the most recent, and well-documented, cycle, 1631-1944) repose, then intracrateral activity starts again.
Typical eruptions closing Vesuvian subcycles were those of 1767, 1779, 1794, 1822, 1872, 1906, and 1944. Each of them caused considerable damage in the towns around the volcano making all of them suffer partial or total destruction at least once during the 1631-1944 cycle. Torre del Greco, on the coast west of Vesuvio, was destroyed or severely damaged three times in that period. Lava flows entered inhabited areas also during some more intense activity in the course of a subcycle, most recently in 1929. Eruptions of this type have been seriously disruptive for life near Vesuvio in the past and would be extremely disturbing, were they to occur today. To cite one example: the 1906 eruption caused heavy tephra falls in the northeastern sector of Vesuvio, causing the collapse of almost all roofs in the towns of that area. Up to 500 people were killed in that event. 26 Peope died much the same way during the most recent eruption in 1944.
After that event, the volcano has most obviously entered one of the longer periods of repose that is maybe to last much longer - up to several centuries - until a new eruptive cycle will begin with a major explosive eruption.
One of the most devastating eruptions after 1631, that of 1794 destroyed the town of Torre del Greco almost completely. The lava flow that did the destruction extended out into the Gulf of Napoli forming a new headland that is well represented in this woodcut. Vesuvion is shown in the culminating explosive phase in the background when lava emission had already ceased. Taken from Alfano and Friedlaender 1928 (see references; bottom of this page).
Such paroxysmal eruptions produce heavy tephra falls, pyroclastic flows, surges, and lahars. Lava flows seem to be uncommon during these events. As the next eruption will probably be a paroxysmal one, primary volcanic hazards are tephra falls and pyroclastic flows and surges. They form a significant threat for a zone including parts of Napoli and the entire belt of towns around the volcano. It is likely that certain phenomena, such as increasing seismicity, deformation, and others, will warn of an impending eruption, as has evidently been the case before the AD 79 and 1631 eruptions. There are, however, serious logistical problems regarding the evacuation of maybe up to a million people in the areas endangered by tephra fall and pyroclastic flows and surges.
For a surprisingly long time, little thought was wasted for the hazards aspect of Vesuvio. One of the first comprehensive papers on volcanic hazards at Vesuvio is that by Barberi et al. (1983), encompassing hazards from lava flows, tephra falls, and glowing avalanches. Recent studies of the volcano and its products in the light of modern volcanology have brought about a rewriting of the eruptive history of the volcano and reinterpretation of some of its most notable eruptions. It was only after these studies, in the early 1990's, that papers with alarming contents based on computer simulations were published in widely-distributed journals. The first of these was a 1990 paper by Barberi et al. in Nature, considering the risk of tephra fallout in the case of a new eruption. Assuming that up to 80 million cubic m of magma had accumulated in Vesuvio's reservoir since 1944, they warned that most buildings would collapse under the weight of tephra in the belt of towns around the volcano. As far as Napoli, up to 20% of all roofs would cave in. This scenario considers an eruption of a size similar to the subcycle-ending events, such as 1906 and 1944, not a paroxysmal eruption like that one in AD 79.
Pyroclastic flow hazards at Vesuvio were recognized first in the 1970's although a courageous but overheard archeologist voiced assumptions that these phenomena might have occurred during the AD 79 eruption as early as 1918 (Merrill 1918, 1920). Barberi et al. (1983) first considered this special kind of hazard and published maps of the areas at risk from pyroclastic flows and surges. However, it was only three years after the 1990 Nature paper by Barberi and his coworkers on fallout risk that computer simulations and reviews of the pyroclastic flow hazard were published in international journals (Scandone et al. 1993, Dobran et al. 1994). Since then, public discussion about the dangers of Vesuvio in Italy is vigorous, and the subject receives high media attention finally. However, everybody talks about corruption in Italy, but the country is far from getting that problem solved. In the case of Vesuvio, the backlog seems even more grave.
Go directly to the Vesuvio reference list
Maybe the best start for those interested in a general way in Vesuvio, there is a nice book to read: Hoffer W (1982) Volcano - the search for Vesuvius. New York: Summit Books, 189 p. It was written by a non-volcanologist open to volcanologic issues in a time when studies at that volcano were in rapid progress. The great papers by Sigurdsson et al. of the mid-1980's were not yet published, thus Hoffer described what destroyed Herculaneum in AD 79 still as mudflows. Many people still have problems accepting that the destructive agent was pyroclastic flows (how else would wood get completely carbonized in the course of less than 2000 years?). Logically, he could not foresee that volcanology in the late 1980's would reveal the most devastating aspect of the 1631 eruption as pyroclastic flows as well (although the mentioning in some historic records of "hot, watery lava" or even water as the most deathly factor in that event should have caused apprehension among volcanologists much earlier), so he vividly describes the death of thousands as being caused by a deluge of unusually fluid lava saturated with water. This is a grave misconception - however, the occurrence of lava flows during the 1631 eruption is still matter of debate (see Rolandi et al. 1993, Rosi et al. 1993, and Carracedo et al. 1993). I any case, Hoffer's book is well readable, illustrating neatly the people of that area and their attitude towards the volcano; it is furthermore important in pointing repeatedly to the extreme risk at Vesuvio.
A compilation of marvellous paintings, drawings and early photographs of many historical eruptions up to the mid-1920's can be found in Alfano GB and Friedlaender I (1928) La storia del Vesuvio. Napoli: K Holm, 71 p. Although volcanologically outdated, this luxuriant book is among the most beautiful Vesuvian references that exist. Unfortunately, it is not widely distributed and many libraries hand it over reluctantly, if at all. Check it, though, if there is a library near your place that has it.
A well-researched article about the AD 79 eruption and recent discoveries at Herculaneum has been published more than ten years ago in the National Geographic, making up for some of Hoffer's deficiencies: Gore R (1984) The dead do tell tales at Vesuvius. National Geographic vol 165 (May 1984): 556-613. Besides showing amazing photos of the excavations at both Herculaneum and Pompeii, Gore tells the story of how those cities really fell victim to the volcano. His report is based on the research done by Sigurdsson and his co-workers and Italian and American archeologists, and is of a notable accuracy.
Who has been infected by the virus of fascination while reading these sources should directly go to the already-mentioned papers by Sigurdsson and his co-workers: Carey S and Sigurdsson H (1987) Temporal vatiations in column height and magma discharge rate during the 79 AD eruption of Vesuvius. Bulletin of the Geological Society of America vol 99: 303-314; Sigurdsson H, Carey S, Cornell W and Pescatore T (1985) The eruption of Vesuvius in 79 AD. National Geographic Research vol 1: 332-387; Sigurdsson H, Cashdollar S and Sparks RSJ (1982) The eruption of Vesuvius in A.D. 79: Reconstruction from historical and volcanological evidence. American Journal of Archaeology vol 86: 39-51. The second of these papers (1985) is a landmark in the history of Vesuvian studies, and it is one of the most thrilling volcanological papers to read. Even though the studies at Vesuvio have continued and some of the findings of Sigurdsson et al. have been discounted by other authors, their reconstruction of the eruption and its implications are basically valid. Vesuvio was shown to be capable of much more than had previously been thought, its AD 79 eruption serving as an extreme example of what should be expected in the future.
More recently, a special issue of the Journal of Volcanology and Geothermal Research was devoted to Vesuvio, displaying the state-of-the-art in the studies of Vesuvio: De Vivo B, Scandone R and Trigila R (eds; 1993) Mount Vesuvius. Journal of Volcanology and Geothermal Research vol 58, 381 p (22 papers). The second paper (Scandone et al. 1993) gives an outline of volcanological observations at Vesuvio and a list of all major eruptive events during the 1631-1944 eruptive cycle. There are descriptions of several large, prehistoric Plinian eruptions, similar to that of AD 79, and each one of devastating proportions. One of the highlights of the volume is the reappraisal of the 1631 eruption in three, somewhat contrasting, papers (Rosi et al. 1993, Rolandi et al. 1993, Carracedo et al. 1993). The matter of debate is whether or not there were lava flows during the 1631 eruption. Basically, Vesuvio tends to produce purely explosive eruptions after long repose periods, and the description of highly mobile lava flows in that eruption are very doubtful. In 1929, very fluid lava was emitted from the volcano, but arriving in inhabited areas, it had lost much of its momentum, moving at a few tens of meters per hour.
For a list of references (being far from complete, but citing many papers that lead to more references), click here .
To BB's volcano home page
This page was last modified 10 December 1995
large (160 k) version of image 
